Atmospheric concentrations and deposition of reactive nitrogen in Grand Teton National Park

摘要

The Grand Teton Reactive Nitrogen Deposition Study (GrandTReNDS) was conducted to provide a more complete look at atmospheric concentrations and deposition fluxes of various reactive nitrogen species in and around Grand Teton National Park (GTNP). Daily measurements of wet deposition, PM_(2.5) composition, and gaseous ammonia and nitric acid concentrations were made at three locations. Weekly measurements of gaseous ammonia were made at eight additional sites. Ammonia concentrations were higher at the western sites; the study average ammonia concentration west of GTNP was 35 nmol m~(-3) and on the east side of the park it was 18 nmol m~(-3). Concentrations of other measured reactive nitrogen species were lower than NH_3 and fairly similar at all sites, with averages of approximately 9, 1, and 3 nmol m~(-3) for ammonium, nitrate, and nitric acid, respectively. Wet deposition of ammonium and dry deposition of ammonia were the largest reactive nitrogen deposition pathways, together accounting for 56% and 62% of the nitrogen deposition on the east and west sides of GTNP, respectively. Nitrogen deposition of measured species totaled 2.38 kg N ha~(-1) west of GTNP at Driggs, ID (6 April to 21 September 2011), 0.85 kg N ha~(-1) west of GTNP at a high-elevation site (28 July to 21 September 2011) and 1.23 kg N · ha~(-1) at a location on the east side of GTNP (15 May to 21 September 2011). These measurements highlight the significant inputs of reactive nitrogen to regional ecosystems over the few months studied, the importance of including NH_3 dry deposition in nitrogen deposition budgets, and the need to conduct further research to capture sources and the annual cycle of deposition. Key Points Reactive nitrogen species in Grand Teton National Park Ammonia concentrations were highest to the west of the park Reduced nitrogen contributed the most to total nitrogen deposition